Hermetically sealed multiple compressor unit



June 1965 w. T. LADUSAW 3,191,403

HERMETICALLY SEALED MULTIPLE COMPRESSOR UNIT Filed Aug. 28, 1963 INVENTOR. MLUAM T LADusAW H \s ATTORNEY United States Patent 3,191,403 HERMETICALLY SEALED MULTIPLE COMPRESSOR UNIT William T. Ladusaw, Jeifersontown, Ky., assignor to General Electric Company, a corporation of New York Filed Aug. 28, 1963, Ser. No. 305,147 2 Claims. (Cl. 62-505) The present invention relates to hermetically sealed rotary compressor units and is more particularly concerned with a hermetically sealed multiple cylinder compressor unit including new and improved means for cooling the drive motor forming part of the hermetically sealed unit.

It is common practice in the field of refrigeration to mount both the refrigerant compressor means and its drive motor within a hermetically sealed casing. In such an arrangement, it is necessary to provide some means for cooling the drive motor in order to maintain its temperature within safe operating limits. One means employed for this purpose is to pass the high pressure discharge gas from the compressor through the drive motor after the high pressure gas has been cooled to a low enough temperature to remove the required amount of heat from the motor.

In one type of hermetically sealed rotary compressor, the motor is disposed in the upper portion of the hermetic casing while the compressor is disposed below the motor and is connected to the motor by a vertical drive shaft. The high pressure discharge gas from the compressor is directed upwardly through passages provided in the motor and is discharged from the casing above the motor. As the gas passes through the motor, it is desirable that any lubricating oil entrained by the gas separate therefrom before the gas is discharged from the casing so that the oil can return by gravity flow to an oil sump 7 provided in the lower portion of the casing. If the velocity of the gas stream is too high, some of the oil deposited on the motor surfaces will be swept upwardly through the motor and discharged from the casing into the refrigeration system. It is therefore necessary to limit the gas velocity by limiting the total volume of refrigerant gas passing through the motor. When a single motor is employed to drive a compressor comprising a plurality of cylinders, it is not feasible to provide gas passages in the p the higher gas flow rate so that any oil which may separate from the gas in the portion of the hermetic casing above the motor cannot readily drain back through the motor against the forces of the upwardly flowing gas stream.

It is a primary object of the present invention to provide a hermetically sealed rotary compressor unit. including a multiple cylinder compressor and an improved means for cooling the motor by high pressure gas dis charged from the compressor.

Another object of the invention is to provide a new and improved hermetically sealed rotary compressor unit ineluding a plurality of cylinders, the unit being so constructed and arranged that the motor is cooled by the discharge from only one of the cylinders while the discharge from the remaining cylinder or cylinders is bypassed around the motor. 7

A further object of the invention is to provide a hermetically sealed multiple cylinder rotary compressor unit so constructed and arranged that only precooled low velocity high pressure gas is passed through the motor for cooling purposes.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In accordance with a preferred embodiment of the present invention, there is provided a hermetically sealed rotary compressor unit adapted to form part of a refrigeration system including a condenser for condensing the refrigerant compressed by the compressor unit and an evaporator for evaporating the condensed refrigerant. The compressor unit comprises a hermetically sealed case enclosing a multiple cylinder compressor in the lower portion thereof and a motor for driving the compressor in the upper portion thereof. The compressor is adapted to withdraw low pressure refrigerant from the evaporator and discharge high pressure refrigerant into the hermetic casing. The high pressure refrigerant then flows from the top of the casing to the condenser. The compressor comprises upper and lower cylinders each including an annular compression chamber separated by a plate forming one end wall of each chamber. In order to cool the motor by means of low velocity high pressure refrigerant discharged from the compressor, the unit is so constructed that only the precooled discharge from the lower compressor cylinder flows upwardly through the motor, the discharge from the upper cylinder being bypassed around the motor introduced into the portion of the casing above the motor where it is mixed with the discharge from the lower compressor unit before flowing to the condenser.

For a better understanding of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a side elevational View partially in section of a hermetically sealed rotary compressor incorporating the present invention;

FIGURE 2 is a partial plan view taken generally along line 2-2 of FIGURE 1; and

FIGURE 3 is a schematic view of a refrigeration system including the compressor of the present invention.

Referring to the drawing, there is illustrated a preferred embodiment of the present invention in the form of a hermetically sealed rotary compressor 1 comprising a hermetic casing 2 containing a compressor 3 in the lower portion thereof and a drive motor 4 in the upper portion thereof. The compressor 3 is primarily supported within the casing 1 by means of a main frame 5 including a bearing structure 6 for supporting or journalling a shaft 7 connecting the motor with the compressor. The main frame 5 in efiect divides the casing 2 into an upper motor compartment and a lower compressor compartment.

The compressor is of the multiple cylinder type including an upper cylinder 8 and a lower cylinder 9 having annular side walls, the cylinders being divided or separated by means of a plate 10 forming the lower end wall of the upper cylinder and the upper end wall of the lower cylinder. The upper end wall of the upper cylinder 8 is formed by the main frame 5 while the lower wall of the lower cylinder is formed by the bearing plate 11 which also supports the lower end of the shaft 7.

the cylinder which vane is biased into engagement with the periphery of the rotor by means such as a spring 19. Thus each cylinder is divided into a high pressure side such as side 9a and a low pressure side such as side 95. During operation of the unit, the rotors l4 and are eccentrically rotated within their respective cylinders by the eccentrics 15 and 16 so that peripheral surfaces of the rotors move progressively into sealing relation with successive portions of the cylinders thereby compressing the gas ahead of the rotors in a direction of rotation thereof in a manner well known in the art.

As may be seen in FIGURE 3 of the drawing, the compressor l is adapted to be connected into a refrigeration system comprising a condenser 21 and an evaporator 22 which receives condensed refrigerant from the condenser 21 through a capillary 25. The hermetic compressor unit withdraws low pressure refrigerant from the evaporator 22 through a suction line 23 and discharges high pressure refrigerant to the condenser 21 through a high pressure discharge line 24.

The low pressure refrigerant withdrawn from the evaporator 22 through the suction line 23 enters a suction port 26 communicating with the low pressure sides of both of the cylinders 8 and 9. More specifically, the suction line passes through the bottom wall 27 of the casing l and upwardly through the bearing plate 11 for communication with the low pressure side 9b of the lower cylinder. An opening 29 in the plate 10 permits flow of the low pressure refrigerant to the upper cylinder 8.

High pressure refrigerant discharged from the high pressure sides of the cylinders 8 and 9 passes through discharge ports 31 or 32 into discharge chambers 33 or 34. Valves 35 and 36 provided at the outlets of the port assure proper compression of the refrigerant issuing from the cylinders and for preventing reverse flow of refrigerant back into the cylinders.

The unit also includes means for lubricating the various bearing surfaces and other moving parts. More specifically, there is provided a body of lubricating oil 40 in a sump formed by the bottom of the compressor casing 1, which body of oil is of sufficient depth to cover the lower end of the shaft 7. The shaft includes a centrifugal pumping arrangement (not shown) for conducting oil from the sump 4t) upwardly through the shaft which includes means for feeding the oil to various surfaces requiring lubrication including the bearing surfaces of the rotors l3 and 14 and bearing 6. Excess oil from hearing 6 collects on the top surface 42 of the main frame 5 and is returned to the sump through an oil passage 43 in lubricant will be carried into the remaining portions of the system such as the condenser 21. To obtain this separation, it has been common practice to discharge the high pressure refrigerant into a portion of the casing such as a space 46 above the motor 4 where its velocity will be reduced so that most of the entrained oil will separate out before the gas enters the discharge line 24. In order also to remove some of the motor heat, the discharge means have been provided for flowing the gas stream over or through the motor 4 before it passes to the condenser 21. To this end, the compressed gas, preferably after suitable cooling has been discharged into the space 47 below the motor 4 from which it flows upwardly through a plurality of passages 49 in the motor to the space 46. Oil separated from the gas stream in these areas returns to the sump through passages 43 and 44.

It has been found that with multiple cylinder compressors, the combined discharge from the plurality of cylinders is of such volume that the gas moves through the motor at such a high velocity as to prevent much of the entrained oil or lubricant separated from the gas in the space 46 above the motor from flowing back to the sump.

In accordance with the present invention, this problem is avoided by so constructing the compressor that the discharge from only one of the cylinders is passed upwardly through the motor. To this end and for reasons which will become more apparent hereinafter, the discharge from the lower cylinder 9 or more specifically the lower discharge chamber 34 is conducted through a conduit 50 extending through the plate 1%, the upper discharge chamber 33 and the main frame 5 into the space47 below the motor 4. Some of the oil entrained by the gas separates out onto the lower surfaces of the motor and returns to the sumpthrough passages 43 and 44 while most of the remaining oil separates in the space 46.

The discharge from the upper discharge chamber 33 is routed around the motor 4, into the space 46 above the motor. While in the disclosed embodiment of the invention, this discharge is shown as being routed through a tube 51 outside the casing, it is to be understood that tube 51 may constitute a gas passage contained entirely within the casing. As the discharge from chamber 33 enters the space 4 d, its velocity is reduced and it becomes mixed with the gas stream which has been passed through the motor. It also has imparted thereto a swirling action due to the rotation of the rotor so that lubricant entrained in this gas stream is separated therefrom and flows downwardly through slots 48 in the motor stator for return to the body of lubricant 40.

By employing the discharge from the lower cylinder 9 to cool the motor, it is possible to provide simple and effective means for cooling this discharge to a temperature such that a sufficient amount of heat will be removed from the motor to maintain the motor at safe operating temperatures. In the illustrated embodiment of the invention, this is done by injecting a small quantity of liquid refrigerant into the compressor chamber 9 as is more fully described and claimed in the copending application of Dean C. Rinehart, Serial No. 139,447, filed September 20, 1961, now Patent No. 3,109,297 and assigned to the same assignee as the present invention. Specifically, there is provided an injector port 53 arranged on the high pressure side 9:: of the cylinder 9 at a point such that the end of the rotor 16 covers the port 53 at all times during each cycle of rotation of the rotor except for a short period during each cycle when the gas pressure in the high pressure side 9a of the cylinder is between, for example, 50 and 95% of the discharge pressure. This liquid refrigerant is provided from the condenser 21 through a conduit 55, which may include a flow restrictor 55 designed to regulate or control the amount of refrigerant introduced through the opening 53 for cooling purposes.

For a further description of the details of operation of this injection cooling means, reference is made to the aforementioned R-inehart application. During each compression cycle of the rotor 16, the cooled liquid refrigerant injected into the cylinder vaporizes or flashes into gaseous form thereby removing heat from the gaseous refrigerant being compressed therein. A substantial reduction in the temperature of the discharge gas is thereby obtained so that the temperature thereof is sufficiently low to provide the desired cooling for the motor 4.

While there has been described what at present is considered to be the preferred embodiment of the present invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is therefore intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure .by Letters Patent of the United States is:

-1. A hermetically sealed rotary compressor unit in combination with a refrigeration system including condensing means for condensing high pressure refrigerant discharged from said compressor and an evaporator, said compressor unit comprising a hermetic casing for containing a high pressure refrigerant gas,

a multiple compressor means in said casing comprising upper and lower annular cylinders separated by a plate forming one end wall of each cylinder,

a motor mounted in the upper portion of said casing above said compressor unit and including a shaft for driving both of said rotors,

a discharge line communicating with the top portion of said casing for conveying high pressure refrigerant to said condensing means,

means for introducing low pressure refrigerant from said evaporator into said cylinders,

upper and lower discharge chambers for each of said cylinders,

said discharge chambers being disposed one above the other and being separated by the said plate,

means for injecting condensed liquid refrigerant from said condensing means into said lower cylinder for cooling the high pressure gas discharged therefrom,

means comprising a conduit communicating with said lower discharge chamber and extending through said upper discharge chamber for directing the cooled high pressure refrigerant discharged from said lower cylinder against the lower end of said motor for passage through said motor,

and means for discharging the high pressure gas discharged fr-om said upper discharge chamber into the portion of said casing above said motor for mixing with the high pressure refrigerant from said lower cylinder before passing out of the casing through said discharge line.

2. A hermetically sealed rotary compressor unit in combination with a refrigeration system including condensing means for condensing high pressure refrigerant discharged from said compressor and an evaporator, said compressor unit comprising a hermetic casing for containing a high pressure refrigerant gas,

a multiple compressor means in said casing comprising upper and lower annular cylinders separated by a plate forming one end wall of each cylinder,

a rotor eccentrically rotatable in each of said cylinders,

a motor mounted in the upper portion of said casing above said compressor unit, and including a shaft for driving both of said rotors,

a discharge line communicating with the top portion of said casing for conveying high pressure refrigerant to said condensing means,

each of said cylinders including a vane slidably supported in the annular wall thereof and biased into engagement with the peripheral surface of the rotor contained in each of said cylinders to divide each of said cylinders into high and low pressure sides,

means including a suction line for introducing low pressure refrigerant from said evaporator into both of said low pressure sides,

upper and lower discharge chambers for each of said cylinders respectively connected to the high pressure sides of said upper and lower cylinders,

said discharge chambers being disposed one above the other and separated by said plate,

means for injecting condensed liquid refrigerant from said condensing means into the high pressure side of said lower cylinder for cooling the high pressure gas discharged therefrom,

means comprising a conduit having its inlet end supported by said plate and communicating with said lower discharge chamber and extending through said upper discharge chamber for directing the cooled high pressure refrigerant discharged from said lower cylinder to the lower end of said motor for passage through said motor,

and means for discharging the high pressure gas discharged from said upper discharge chamber into said casing above said motor for mixing with the high pres-sure refrigerant from said lower cylinder before passing out of the casing through said discharge line.

References Cited by the Examiner UNITED STATES PATENTS 2,084,341 6/37 Hornaday 62469 X 3,11 1,820 11/ 63 Atchison 62505 a EDWARD 1. MICHAEL, Primary Examiner.

MEYER PER LIN, Examiner. 

1. A HERMETICALLY SEALED ROTARY COMPRESSOR UNIT IN COMBINATION WITH A REFRIGERATION SYSTEM INCLUDING CONDENSING MEANS FOR CONDENSING HIGH PRESSURE REFRIGERANT DISCHARGED FROM SAID COMPRESSOR AND AN EVAPORATOR, SAID COMPRESSOR UNIT COMPRISING A HERMETIC CASING FOR CONTAINING A HIGH PRESSURE REFRIGERANT GAS, A MULTIPLE COMPRESSOR MEANS IN SAID CASING COMPRISING UPPER AND LOWER ANNULAR CYLINDERS SEPARATED BY A PLATE FORMING ONE END WALL OF EACH CYLINDER, A MOTOR MOUNTED IN THE UPPER PORTION OF SAID CASING ABOVE SAID COMPRESSOR UNIT AND INCLUDING A SHAFT FOR DRIVING BOTH OF SAID ROTORS, A DISCHARGE LINE COMMUNICATING WITH TOP PORTION OF SAID CASING FOR CONVEYING HIGH PRESSURE REFRIGERANT TO SAID CONDENSING MEANS, MEANS FOR INTRODUCING LOW PRESSURE REFRIGERANT FROM SAID EVAPORATOR INTO SAID CYLINDERS, UPPER AND LOWER DISCHARGE CHAMBERS FOR EACH OF SAID CYLINDERS, SAID DISCHARGE CHAMBERS BEING DISPOSED ONE ABOVE THE OTHER AND BEING SEPARATED BY THE SAID PLATE, MEANS FOR INJECTING CONDENSED LIQUID REFRIGERANT FROM SAID CONDENSING MEANS INTO SAID LOWER CYLINDER FOR COOLING THE HIGH PRESSURE GAS DISCHARGED THEREFROM, MEANS COMPRISING A CONDUIT COMMUNICATING WITH SAID LOWER DISCHARGE CHAMBER AND EXTENDING THROUGH SAID UPPER DISCHARGE CHAMBER FOR DIRECTING THE COOLED HIGH PRESSURE REFRIGERANT DISCHARGED FROM SAID LOWER CYLINDER AGAINST THE LOWER END OF SAID MOTOR FOR PASSAGE THROUGH SAID MOTOR, AND MEANS FOR DISCHARGING THE HIGH PRESSURE GAS DIS CHARGED FROM SAID UPPER DISCHARGED CHAMBER INTO THE PORTION OF SAID CASING ABOVE SAID MOTOR FOR MIXING WITH THE HIGH PRESSURE REFRIGERANT FROM SAID LOWER CYLINDER BEFORE PASSING OUT OF THE CASING THROUGH SAID DISCHARGE LINE. 